Method and device for producing medium-thickness plates with high thickness precision through cvc steckel mill

ABSTRACT

A method and a device for producing medium-thickness plates with high thickness precision through a CVC steckel mill. The method includes the following: heating a blank in the heating furnace, and roughly descaling by the descaling machine; enabling the blank to enter the rolling mill, after multi-pass flat rolling, carrying out multi-pass rolling, carrying out linkage rolling of the rolling mill and the coiler furnaces in the rolling process, and enabling the rolling tension to reach a set value; controlling the temperatures of the coiler furnace to a set value in the coiling process; and in the rolling process, starting 30-70% of the original flow of cooling water of the working roll of the rolling mill; and after rolling is finished, finishing the production process through the laminar cooling system and the hot straightening machine respectively.

TECHNICAL FIELD

The present disclosure relates to the technical field of steel rolling, in particular to a method and a device for producing medium-thickness plates with high thickness precision through a CVC steckel mill.

BACKGROUND

A traditional medium-thickness plate rolling mill is limited by too fast temperature drop of rolled pieces in the rolling process when a conventional medium-thickness plate or high-thickness plate rolling line are used for producing thick and thin steel plates. As the steel plate becomes thinner and thinner and the rolled piece becomes longer and longer in the rolling process, the temperature drop of the steel plate becomes faster and faster, steel for luxury cruise ships with the thickness of 4-8 mm and the width of 2000-3100 mm, high-strength steel with the yield strength of 890-1100 MPa, steel for Katerpiller engineering machinery and the like are produced. The steel is difficult in stable production, low in efficiency and high in energy consumption. The thickness fluctuation range of the steel plate is generally 0-1.2 mm, which is a problem urgently needing to be solved.

The traditional medium-thickness plate rolling mill is used for producing steel for luxury cruise ships with the thickness of 4-8 mm and the width of 2000-3100 mm, high-strength steel with the yield strength of 890-1100 MPa, steel for Katerpiller engineering machinery. The thickness fluctuation is large. When the steel plate is applied to the luxury cruise ship construction process, the weight of the whole ship is increased, the energy consumption is increased, the gravity center of a ship body moves upwards, and the comfort and the safety of the luxury cruise ship are affected, so that the requirement of luxury cruise ship construction is difficult to meet. When the high-strength steel with the yield strength of 890-1100 MPa is applied to a crane jib or a cement pump truck, the high-strength steel is subjected to large thickness fluctuation and poor formability of the jib and the like. Meanwhile, the energy consumption is increased due to overweight of the whole truck. When the high-strength steel is applied to an excavator such as a Caterpillar truck, the high-strength steel is subjected to large thickness fluctuation and high energy consumption due to overweight of the excavator.

SUMMARY

The present disclosure aims to provide a method and a device for producing medium-thickness plates with high thickness precision through a CVC steckel mill to solve the problems existing in the prior art, so that the steel plate is small in thickness fluctuation and small in thickness precision range, and the effective load is improved.

In order to achieve the purpose, the present disclosure provides the following scheme.

The present disclosure provides a method for producing medium-thickness plates with high thickness precision through a CVC steckel mill, comprising the following steps:

-   -   step one, heating a blank in the heating furnace, and roughly         descaling by the descaling machine;     -   step two, enabling the blank to enter the rolling mill which is         a CVCplus steckel mill, after multi-pass flat rolling, carrying         out multi-pass rolling, carrying out linkage rolling of the         rolling mill and the coiler furnaces in the rolling process,         enabling the rolling tension to reach a set value, optimizing a         second-stage model procedure of rolling, and using the rolling         technology as much as possible, wherein the thinner the steel         plate is rolled, the more the rolling passes are; for example,         the steel plate with the thickness of 4 mm is rolled, the         original second-stage model adopts the technology of eight flat         rolling passes and five rolling passes, and the original         technology is replaced by six flat rolling passes and seven         rolling passes after the second-stage model is optimized, so         that the rolling temperature can be increased by 30° C. to 60°         C., and the thickness uniformity is further improved;         controlling the temperature of the coiler furnace to a set value         in the coiling process, wherein during rolling, according to         different steel plate rolling thicknesses, different working         roll cooling water flow control is adopted, and 30-70% of the         original flow of working roll cooling water of the rolling mill         is started; and     -   step three, after rolling is finished, finishing the production         process through the laminar cooling system and the hot         straightening machine respectively, wherein a second-stage model         and a first-stage automatic control program are established, and         all functions can be automatically realized.

Optionally, in the second step, the temperature range of the coiler furnace is controlled between 850° C. and 950° C. according to the width and the mechanical property of the rolled steel plate.

Optionally, in the second step, the rolling tension of the coiler furnace can be controlled according to the width and the mechanical property of the rolled steel plate, a tension linear function curve is established, and the rolling tension range between the coiler furnace and the rolling mill ranges from 15 tons to 25 tons.

Optionally, in the second step, the axial movement amount of the working roll is changed in the last three rolling passes. According to the width and the mechanical property of the rolled steel plate, the axial movement control technology of the working roll is optimized. Meanwhile, the axial movement amount of three passes at the end of finish rolling is optimized according to the thickness of the steel plate. The use of roll bending force is optimized according to the rolled plate shape condition of the three passes at the end of finish rolling. The roll bending force is increased or decreased aiming at edge waves and medium waves of the steel plate in the rolling process. The transverse thickness uniformity of the steel plate is controlled by adjusting the axial movement amount of the CVCplus steckel mill. By adjusting the heating temperatures of the front coiler furnace and the rear coiler furnace of the rolling mill, the longitudinal temperature drop and the temperature difference of the steel plate are effectively reduced, and the longitudinal thickness uniformity and the transverse thickness uniformity of the steel plate are improved. Meanwhile, the rolling technology in the second-stage model and tension control of the front coiler furnace and the rear coiler furnace are optimized, and the transverse and longitudinal thickness uniformity control of the steel plate is achieved.

The device for producing medium-thickness plates with high thickness precision through a CVC steckel mill provided by the present disclosure comprises a heating furnace, a descaling machine, a rolling mill, a laminar cooling system and a hot straightening machine which are sequentially arranged; and the rolling mill is a CVCplus steckel mill, a front coiler furnace is arranged at the front end of the rolling mill, and a rear coiler furnace is arranged at the rear end of the rolling mill.

Compared with the prior art, the present disclosure has the following technical effects.

By means of the technical advantages of the working roll axial movement control technology and the rolling technology of the CVCplus steckel mill, a production control technology with the steel plate thickness tolerance meeting the high-precision range of 0-0.2 mm is developed. The transverse thickness uniformity of the steel plate is controlled by adjusting the axial movement amount of the CVCplus steckel mill. By adjusting the heating temperatures of the front coiler furnace and the rear coiler furnace of the rolling mill, the longitudinal temperature drop and the temperature difference of the steel plate are effectively reduced, and the longitudinal thickness uniformity and the transverse thickness uniformity of the steel plate are improved. Meanwhile, the rolling technology in the second-stage model and tension control of the front coiler furnace and the rear coiler furnace are optimized, and the transverse and longitudinal thickness uniformity control of the steel plate is achieved. The second-stage model procedure of rolling is optimized, and the rolling technology is used as much as possible. The thinner the steel plate is rolled, the more the rolling passes are, so that the rolling temperature can be increased by 30° C. to 60° C., and the thickness uniformity is further improved. After detection by a three-point thickness gauge, an ultrasonic thickness gauge and the like, the thickness tolerance of the steel plate meets the requirement of 0-0.2 mm, breaking through the defects that the tolerance range of a current medium-thickness plate product is 0-1.2 mm control level, the difference of the same plate is smaller than or equal to 0.05 mm, and the weight of the steel plate is reduced by about 3-9%. Due to the fact that a large number of steel plates with the thickness precision range of 0-0.2 mm are used for replacing the steel plates with the original thickness precision range of 0-1.2 mm in luxurious cruise ships, mine cars, excavators, cranes and the like, the weight of the car is reduced, and the effective load is improved, so that the CO₂ emission is reduced.

DRAWINGS

To more clearly illustrate the embodiment of the present disclosure or the technical scheme in the prior art, the following briefly introduces the attached FIGURES to be used in the embodiment. Apparently, the attached FIGURES in the following description show merely some embodiments of the present disclosure, and those skilled in the art may still derive other drawings from these attached FIGURES without creative efforts.

FIG. 1 is a layout schematic diagram of a device for producing medium-thickness plates with high thickness precision through a CVC steckel mill in the present disclosure.

DESCRIPTION

The following clearly and completely describes the technical scheme in the embodiments of the present disclosure with reference to the attached FIGURES in the embodiments of the present disclosure. Apparently, the described embodiments are merely a part rather than all of the embodiments of the present disclosure. Based on the embodiment in the present disclosure, all other embodiments obtained by the ordinary technical staff in the art under the premise of without contributing creative labor belong to the scope protected by the present disclosure.

The present disclosure aims to provide a method and a device for producing medium-thickness plates with high thickness precision through a CVC steckel mill to solve the problems existing in the prior art, so that the steel plate is small in thickness fluctuation and small in thickness precision range, and the effective load is improved.

To make the foregoing objective, features and advantages of the present disclosure clearer and more comprehensible, the present disclosure is further described in detail below with reference to the attached FIGURES and specific embodiments.

The device for producing medium-thickness plates with high thickness precision through a CVC steckel mill provided by the present disclosure, as shown in FIG. 1 , comprises a heating furnace 1, a descaling machine 2, a rolling mill 4, a laminar cooling system 6 and a hot straightening machine 7 which are sequentially arranged; and the rolling mill 4 is a CVCplus steckel mill, a front coiler furnace 3 is arranged at the front end of the rolling mill 4, and a rear coiler furnace 5 is arranged at the rear end of the rolling mill 4. Based on the layout form of the device, the present disclosure provides a method for producing medium-thickness plates with high thickness precision through a CVC steckel mill, comprising the following steps:

-   -   step one, heating a blank in the heating furnace 1, and roughly         descaling by the descaling machine 2;     -   step two, enabling the blank to enter the rolling mill 4 which         is a CVCplus steckel mill, after multi-pass flat rolling,         carrying out multi-pass rolling, carrying out linkage rolling of         the rolling mill and the coiler furnaces in the rolling process,         enabling the rolling tension to reach a set value, optimizing a         second-stage model procedure of rolling, and using the rolling         technology as much as possible, wherein the thinner the steel         plate is rolled, the more the rolling passes are; for example,         the steel plate with the thickness of 4 mm is rolled, the         original second-stage model adopts the technology of eight flat         rolling passes and five rolling passes, and the original         technology is replaced by six flat rolling passes and seven         rolling passes after the second-stage model is optimized, so         that the rolling temperature can be increased by 30° C. to 60°         C., and the thickness uniformity is further improved;         controlling the temperature of the coiler furnace to a set value         in the coiling process, wherein during rolling, according to         different steel plate rolling thicknesses, different working         roll cooling water flow control is adopted, and 30-70% of the         original flow of working roll cooling water of the rolling mill         4 is started, and the temperature range of the front coiler         furnace 3 and the temperature range of the rear coiler furnace 5         are controlled between 850° C. and 950° C. according to the         width and the mechanical property of the rolled steel plate. The         rolling tension of the coiler furnace can be controlled         according to the width and the mechanical property of the rolled         steel plate, and the rolling tension between the front coiler         furnace 3 and the rolling mill 4 and the rolling tension between         the rear coiler furnace 5 and the rolling mill 4 range from 15         tons to 25 tons. The axial movement amount of the working roll         is changed in the last three rolling passes. According to the         width and the mechanical property of the rolled steel plate, the         axial movement control technology of the working roll is         optimized. Meanwhile, the axial movement amount of three passes         at the end of finish rolling is optimized according to the         thickness of the steel plate. The use of roll bending force is         optimized according to the rolled plate shape condition of the         three passes at the end of finish rolling. The roll bending         force is increased or decreased aiming at edge waves and medium         waves of the steel plate in the rolling process. The transverse         thickness uniformity of the steel plate is controlled by         adjusting the axial movement amount of the CVCplus steckel mill.         By adjusting the heating temperatures of the front coiler         furnace 3 and the rear coiler furnace 5, the longitudinal         temperature drop and the temperature difference of the steel         plate are effectively reduced, and the longitudinal thickness         uniformity and the transverse thickness uniformity of the steel         plate are improved. Meanwhile, the rolling technology in the         second-stage model and tension control of the front coiler         furnace and the rear coiler furnace are optimized, and the         transverse and longitudinal thickness uniformity control of the         steel plate is achieved.

In the third step, after rolling is finished, the production process is finished through the laminar cooling system 6 and the hot straightening machine 7 respectively. A second-stage model and a first-stage automatic control program are established, and all functions can be automatically realized.

According to the disclosed control technology, compared with the thin rolling capacity of a conventional medium-thickness plate rolling mill, in the control technology for axial movement of the CVCplus working roll of the steckel mill, two coiler furnaces are simultaneously arranged at the front and rear ends of a rack, and the highest temperature of the coiler furnaces can reach 950° C. In the rolling process of the steel plate, the steel plate is rolled by the rolling mill 4 from the front coiler furnace 3 to enter the rear coiler furnace 5 for heat preservation. The rolling temperature of the steel plate with the thickness specification of 4-8 mm is effectively increased, the temperature drop of the steel plate is controlled, and the thickness uniformity is improved to the maximum extent. Meanwhile, the rolling tension of the coiler furnace and the roll bending force of the rolling mill 4 are both very beneficial to the thickness stability of thickness specification. Steel for luxury cruise ships, high-strength steel with the yield strength of 890 MPa to 1100 MPa, steel for Caterpillar engineering machinery and the like are produced. The steel is high in efficiency and stable in quality. The average thickness fluctuation range is 0 to 0.2 mm, the difference of the same plate is smaller than or equal to 0.05 mm, and the weight of the steel plate is reduced by about 3-9% after the thickness is more uniform. Due to the fact that a large number of steel plates with the thickness precision range of 0-0.2 mm are used for replacing the steel plates with the original thickness precision range of 0-1.2 mm in luxurious cruise ships, mine cars, excavators, cranes and the like, the weight of the car is reduced, and the effective load is improved, so that the CO₂ emission is reduced.

Embodiment I

According to a method for producing medium-thickness plates with high thickness precision through a CVC steckel mill, the thickness of the steel plate is 4 mm, the width of the steel plate is 3050 mm, the steel type is AH36, and the average thickness tolerance of the steel plate is required to be 0-0.2 mm according to the technical requirement.

According to the embodiment, one rolling plate is selected as an AH36 luxury cruise ship steel blank, the actual size of the blank is 150*3150*6000 mm, the thickness of the finished product is 4 mm, the width of the finished product is 3050 mm, thirteen rolling passes are carried out and divided into two rolling stages, namely six flat rolling passes in the first stage and seven rolling passes in the second stage (the seventh to the thirteenth rolling passes). Details are as follows:

Firstly, the heating temperature of the blank in the heating furnace 1 is increased to 1230° C., and the heating furnace 1 is subjected to rough descaling by the descaling machine 2 after tapping.

Secondly, the blank enters the rolling mill 4, the second-stage model is optimized from eight flat rolling passes and five rolling passes to six flat rolling passes and seven rolling passes, the blank enters a rolling mode in the rear coiler furnace 5 in the seventh pass, and rolling is finished by the front coiler furnace 3, the rear coiler furnace 5 and the CVCplus four-roll reversible rolling mill together.

Thirdly, in the coiling process of the front coiler furnace 3 and the rear coiler furnace 5 for a rolled piece, the temperatures of the front coiler furnace 3 and the rear coiler furnace 5 are controlled between 900° C. and 910° C.

Fourthly, in the rolling process, the tension between the CVCplus four-roll reversible rolling mill and the front coiler furnace 3 and the tension between the CVCplus four-roll reversible rolling mill and the rear coiler furnace 5 are kept to be 20 tons.

Fifthly, the CVCplus four-roll reversible rolling mill rolls for the last three passes, and the CVC axial movement amount is limited within 50 mm and is unsuitable to be too large.

Sixthly, the CVCplus four-roll reversible rolling mill rolls for the last three passes, the reduction rate of the third last pass is about 18%, the reduction rate of the second last pass is about 16%, and the reduction rate of the last pass is about 13%.

Seventhly, in the rolling process, the first-stage limited opening of roll cooling water of the CVCplus four-roll reversible rolling mill is only 50% of the original flow.

Eighthly, after rolling is finished, the production process is finished through the laminar cooling system 6 and the hot straightening machine 7 respectively.

Embodiment II

According to a method for producing medium-thickness plates with high thickness precision through a CVC steckel mill, the thickness of the steel plate is 4.5 mm, the width of the steel plate is 3000 mm, the steel type is Q1100 (with the yield strength of 1100 MPa), and the thickness tolerance of a single steel plate is required to be 0-0.2 mm according to the technical requirement.

According to the embodiment, one rolling plate is selected as a Q1100 ultrahigh-strength steel blank, the actual size of the blank is 150*3100*5800 mm, the thickness of the finished product is 4.5 mm, the width of the finished product is 3000 mm, thirteen rolling passes are carried out and divided into two rolling stages, namely six flat rolling passes in the first stage and seven rolling passes in the second stage (the seventh to the thirteenth rolling passes). Details are as follows:

Firstly, the heating temperature of the blank in the heating furnace 1 is increased to 1250° C., and the heating furnace 1 is subjected to rough descaling by the descaling machine 2 after tapping.

Secondly, the blank enters the CVCplus four-roll reversible rolling mill, the second-stage model is optimized from eight flat rolling passes and five rolling passes to six flat rolling passes and seven rolling passes, the blank enters a rolling mode in the rear coiler furnace 5 in the seventh pass, and rolling is finished by the front coiler furnace 3, the rear coiler furnace 5 and the CVCplus four-roll reversible rolling mill together.

Thirdly, in the coiling process of the front coiler furnace 3 and the rear coiler furnace 5 for a rolled piece, the temperatures of the front coiler furnace 3 and the rear coiler furnace 5 are controlled between 930° C. and 950° C.

Fourthly, in the rolling process, the tension between the CVCplus four-roll reversible rolling mill and the front coiler furnace 3 and the tension between the CVCplus four-roll reversible rolling mill and the rear coiler furnace 5 are kept to be 25 tons.

Fifthly, the CVCplus four-roll reversible rolling mill rolls for the last three passes, and the CVC axial movement amount is limited within 35 mm and is unsuitable to be too large.

Sixthly, the CVCplus four-roll reversible rolling mill rolls for the last three passes, the reduction rate of the third last pass is about 16%, the reduction rate of the second last pass is about 14%, and the reduction rate of the last pass is about 10%.

Seventhly, in the rolling process, the first-stage limited opening of roll cooling water of the CVCplus four-roll reversible rolling mill is only 30% of the original flow.

Eighthly, after rolling is finished, the production process is finished through the laminar cooling system 6 and the hot straightening machine 7 respectively.

In the description of the present disclosure, it needs to be illustrated that the indicative direction or position relations of the terms such as “center”, “top”, “bottom”, “left”, “right”, “vertical”, “horizontal”, “inside” and “outside” are direction or position relations illustrated based on the attached FIGURES, just for facilitating the description of the present disclosure and simplifying the description, but not for indicating or hinting that the indicated device or element must be in a specific direction and is constructed and operated in the specific direction, the terms cannot be understood as the restriction of the present disclosure. Moreover, the terms such as “first” and “second” are just used for distinguishing the description, but cannot be understood to indicate or hint relative importance.

Specific examples are used for illustration of the principles and implementation methods of the present disclosure. The description of the above-mentioned embodiments is used to help illustrate the method and its core principles of the present disclosure. In addition, those skilled in the art can make various modifications in terms of specific embodiments and scope of application in accordance with the teachings of the present disclosure. In conclusion, the content of this specification shall not be construed as a limitation to the present disclosure.

LIST OF REFERENCE SYMBOLS

-   -   1 heating furnace     -   2 descaling machine     -   3 front coiler furnace     -   4 rolling mill     -   5 rear coiler furnace     -   6 laminar cooling system     -   7 hot straightening machine 

What is claimed is:
 1. A method for producing medium-thickness plates with high thickness precision through a CVC steckel mill, the method comprising: heating a blank in a heating furnace, and roughly descaling using a descaling machine; enabling the heated blank to enter a rolling mill, after multi-pass flat rolling, carrying out multi-pass rolling, carrying out linkage rolling of the rolling mill and a coiler furnace in the rolling process, and enabling a rolling tension to reach a set value, controlling the temperatures of the coiler furnace to a set value in the coiling process, and in the rolling process, starting 30-70% of an original flow of cooling water of a working roll of the rolling mill; and finishing, after the rolling process is finished, the production process through a laminar cooling system and a hot straightening machine, respectively.
 2. The method of claim 1, wherein in the rolling mill, a temperature range of the coiler furnace is controlled between 850° C. and 950° C.
 3. The method of claim 1, wherein in the rolling mill, the rolling tension between the coiler furnace and the rolling mill is in a range between 15 tons and 25 tons.
 4. The method of claim 1, wherein in the rolling mill: an axial movement amount of the working roll is changed in the last three rolling passes, and a roll bending force is increased or decreased aiming at edge waves and medium waves of a steel plate in the rolling process.
 5. A device for producing medium-thickness plates with high thickness precision through a CVC steckel mill using the method of claim 1, the device comprising: a heating furnace; a descaling machine; a rolling mill; a laminar cooling system and a hot straightening machine which are sequentially arranged; a front coiler furnace arranged at a front end of the rolling mill; and a rear coiler furnace arranged at a rear end of the rolling mill. 